The invention relates to an adjusting device for the throttle flap of an internal combustion engine of a motor vehicle utilizing a mechanical transmission device between an actuating lever and the throttle flap for transmitting movement of the actuating lever to the throttle flap. Also included is a mechanism for introducing other influencing and correcting variables into the transmission device, independently of the movement of the actuating lever, via a servo-motor adjustable as a function of these influencing and correcting variables and a gear wheel acting on the transmission device.
An adjusting device of this general type is known from DE OS 3,628,456 wherein there is a mechanical transmission device with a deflectable flexible part, such as a toothed belt or the core of a Bowden pull, guided via a wheel which is supported displaceably by means of a motor or an electromagnet. A basic shift of the control element by means of an actuating lever can thus have a correcting movement superimposed on it. This movement occurs as a function of other influencing variables, such as drive slip and engine drag torque. In this adjusting device, it is necessary to use a deflectable flexible part which is exposed to special loads at the deflection on the wheel and exerts a load on the wheel support with its entire pull. When the deflectable part is guided to and from the wheel in a non-parallel way, there is no constant transmission ratio between the wheel displacement and the lengthening or shortening of the transmission device.
The object on which the invention is based is to design an adjusting device of this general type mentioned in the introduction, in such a way, that the introduction of the other influencing and correcting variables takes place without the use of a deflectable flexible part. This allows for a greater freedom in the choice of the transmission device.
In an adjusting device of the particular general type, the object is achieved by having a planetary gear inserted in the transmission device. The planetary gear has an outer gear wheel, a sun gear wheel, and a planet carrier carrying planet gear wheels, wherein these elements are respectively connected operativelY to the actuating lever, to the servo-motor and to the throttle flap.
In this adjusting device the introduction of the basic movement, correcting movement and the transfer of the shifting movement to the control element take place as a result of purely rotary movements. With the advantageous use of the servo-motor, there is no need for: a longitudinally displaceable transmission means between the electric servo motor and the planetary gear, or for a flexible pliable part in the transmission device. The transmission ratios between the individual elements of the compact planetary gear are always independent of the position of these elements.
Having the outer gear wheel connected to the actuating lever, the sun gear wheel to the servo-motor, and the planet-gear carrier to the throttle flap, all allows for a favorable spatial design of the planetary gear and of its connections. This also allows for an advantageous reduction ratio between the servo-motor and control element.
The influencing and correcting variables acting on the servo-motor are: the slip of the vehicle gear wheels, the driving speed or transmission ratio between the shifts of the actuating lever and of the throttle flap. Also the selected gear of a vehicle transmission can be an input superimposed on the basic shifts introduced by the actuating lever. In particular, the transmission ratio between the actuating lever and the control element can be varied as a result of a superimposed rotary movement of the servo-motor and of the element connected to it in the planetary gear mechanism. Specifically, during a rotary movement of the servo-motor which is constant in relation to the rotary movement of the element connected to the actuating lever, a constant variation in the transmission ratio is obtained and, with a non-constant rotary movement of the servo-motor, a non-constant transmission ratio is obtained. Thus, degressive, constant, or progressive transmission ratios between the actuating lever and control element can be put into effect as a function of the gears selected. The particular correcting variables can be determined in a known way by means of fields of characteristics.
By having the positions of the actuating lever, servo-motor and throttle flap each determined by an actual-value transmitter, and by having the sum of the position values of the actuating lever and servo-motor compared with the position value of the throttle flap in a computing unit, allows any fault in the mechanical transmission device to be detected. This is possible since the position of the control element depends unmistakenly on the sum of the positions of the actuating lever and servo-motor. This fact can he utilized in the event of a fault in the mechanical transmission device between the actuating lever and that element of the planetary gear connected to it. That element is brought, as a result of restoring spring, into an end position corresponding to the idling position and is retained there. The position value determined by the actual-value transmitter of the actuating lever is transmitted to the servo-motor and the latter is adjusted according to this position value in addition to the other influencing and correcting variables. This makes it possible for the transmission of the position of the actuating lever to be taken over by the servo-motor.
In contrast, in the adjusting device of the general aforementioned type, both the basic and the correcting shift are no longer possible in the event of a fault in the transmission device, for example a break of the flexible pliant part.
In the event of a fault in the electrical device supplying the servo-motor, the adjusting device of the sun gear wheel of the planetarY gear (connected to the servo-motor) is brought into an intermediate position and retained there as a result of spring force from a tension spring. This allows an unchanged complete basic movement by means of the actuating lever, without the possibility of correcting movements, since, in the indicated intermediate position of the servo-motor, the actuating lever and the control element assume suitable positions.
By having the servo-motor shifted into the intermediate position by means of a rack which, when the servo-motor is currentless, is shifted up against an adjustable stop as a result of the spring force of tension spring and wherein an adjustable stop is formed by a stop rod which is retained in one end position by means of a magnet and where the magnet becomes currentless at the same time as the servo-motor, the stop is shifted in the direction of the rack into a second end position as a result of spring force of compression spring. Also the rack then engages on the sun gear wheel shaft. These provide an advantageous organization of elements, which allow the servo-motor and the associated element of the planetary gear to be shifted and retained in an intermediate position Thus, the stop rod, retracted under fault-free circumstances and forming the adjustable stop, allows an unimpeded movement of the rack in both directions. The springs, activated in the event of a fault without any outlay in control terms, ensure the necessary shifting and retention of the servo-motor in a simple way.
It is advantageous if that element of the planetary gear connected to the throttle flap, is fixedly connected in terms of rotation to a drive gear wheel and the shaft of the throttle flap is connected to a driven gear wheel that is driven by an endless flexible drive, or the driven gear wheel. This allows for a simple and reliable direct connection between these parts in less space. This connection by means of rotary parts is also advantageous because the parts to be connected execute rotary movements.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.